CN116670356A

CN116670356A - Method for decolorizing textile

Info

Publication number: CN116670356A
Application number: CN202180087888.5A
Authority: CN
Inventors: 葛仪文; 姚磊; 陈学聪; 冯世隆; 林婉婷; 陈立鸿; 余莉萤
Original assignee: Hong Kong Research Institute of Textiles and Apparel Ltd
Current assignee: Hong Kong Research Institute of Textiles and Apparel Ltd
Priority date: 2021-02-24
Filing date: 2021-02-24
Publication date: 2023-08-29
Also published as: WO2022178704A1

Abstract

A method for decolorizing a dyed textile comprising synthetic fibers and a disperse dye, the method comprising contacting the dyed textile with a supercritical fluid to extract at least a portion of the disperse dye from the textile into the supercritical fluid and form an at least partially decolorized textile.

Description

Method for decolorizing textile

Technical Field

The present disclosure relates to a method of using supercritical fluids (e.g., supercritical CO ₂ ) As a reusable dye extractant for decolorizing textiles such as post-consumer textiles containing polyethylene terephthalate (PET).

Background

Over 75% of the man-made textiles were produced using PET or PET/cotton blends. PET textiles recovered using conventional methods retain their original color after recovery and/or separation and cannot be mixed or woven together to form new textiles in an industrial-grade production process. The color of the recycled PET is limited and the potential new applications of the recycled PET may be limited. In order to effectively recycle PET-containing textiles for new textiles, it is necessary to decolorize the recycled PET before regenerating the new textiles.

One conventional method for decolorizing recycled textiles is through the use of bleaching agents. Textiles made from PET or PET/cotton blends, for example, are bleached with bleaching agents such as sodium hypochlorite, sodium chlorite, sodium dithionite, sodium bisulphite formaldehyde and hydrogen peroxide to eliminate dyes inside the fabric. However, these bleaching agents can create problems such as breaking the fiber structure, forming toxic chemicals, and generating large amounts of hazardous effluents and exhaust gases.

Disperse dyes commonly used for PET dyeing are hydrophobic and are embedded within PET fibers. Removal of disperse dye molecules by chemical means can disrupt the structure and integrity of PET-containing textiles.

The reactive agents used in bleaching also produce toxic byproducts containing heavy metals, carcinogens, and Volatile Organic Compounds (VOCs). The handling and disposal of these toxic byproducts is expensive and time consuming.

Thus, recycling PET-containing textiles is far from profitable and sustainable, in part due to the poor physical properties of the recycled fibers and the cost of disposal and disposal of the waste generated in the decolorization process.

Other decolorization methods are currently only suitable for extracting disperse dyes in textile effluents. Adsorption of activated carbon, for example, is commonly used to remove disperse dyes from wastewater.

Enzymes, fungi and microorganisms have also been found to biodegrade soluble dyes in textile wastewater. Methods have also been developed involving chemical reactions of dyes with ozone or semi-conductive metals to treat dyes present in textile effluents. Such methods may be ineffective and/or not feasible for discoloration of the recycled PET.

Accordingly, there is a need to develop improved methods for decolorizing textiles comprising synthetic fibers such as PET.

Disclosure of Invention

The present disclosure provides methods for decolorizing textiles comprising synthetic fibers (e.g., PET) by supercritical fluid extraction. When carbon dioxide is above its critical point, 31 ℃ and 73 bar, it shows excellent mass transfer and permeation effects due to its low viscosity and near zero surface tension. Without wishing to be bound by theory, it is believed that the synthetic textile fibers become "swollen" at high temperatures, which allows the supercritical fluid to penetrate deep into the dyed textile fibers to dissolve and extract the dye from the fibers. Supercritical fluids also have adjustable solvent strength and density, which can be varied by varying the temperature or pressure. The temperature and pressure are generally positively correlated with the solubility of the dye in the supercritical fluid, and better decolorizing performance can be achieved at higher temperatures and pressures. Since most disperse dyes are nonpolar, when a relatively nonpolar supercritical fluid (e.g., supercritical CO ₂ ) In this case, extraction of the dye and decolorization of the synthetic fibers dyed with disperse dyes are advantageous. Dissolved in supercritical CO ₂ The disperse dye of (c) can be physically separated from the textile by the methods described herein, thereby causing at least partial decolorization of the textile.

In a first aspect, provided herein is a method of decolorizing a dyed textile comprising synthetic fibers and a disperse dye, the method comprising contacting the dyed textile with a supercritical fluid to extract at least a portion of the disperse dye from the textile into the supercritical fluid and form an at least partially decolorized textile.

In certain embodiments, the supercritical fluid does not comprise a surfactant.

In certain embodiments, the synthetic fibers comprise polyesters, polyamides, polyolefins, acrylic, acetate, polyurethane, or combinations thereof.

In certain embodiments, the synthetic fibers comprise polyethylene terephthalate (PET).

In certain embodiments, the disperse dye is selected from the group consisting of: acridine, anthraquinone, arylmethane, azo, cyanine, diazo, nitro, nitroso, phthalocyanine, quinone, azine, indamine (indamines), indophenol, oxazine, oxaketone, thiazine, thiazole, xanthene, fluorine, and combinations thereof.

In certain embodiments, the supercritical fluid comprises carbon dioxide, acetone, methanol, ethanol, and propanol, and mixtures thereof.

In certain embodiments, the extraction is performed at a temperature between 60 ℃ and 150 ℃.

In certain embodiments, the extraction is performed at a temperature between 90 ℃ and 130 ℃.

In certain embodiments, the extraction is performed at a pressure between 140 bar and 280 bar.

In certain embodiments, the extraction is performed at a pressure between 210 bar and 280 bar.

In certain embodiments, the at least partially decolorized textile has a tensile strength that does not vary by more than 10% of the tensile strength of the dyed textile.

In certain embodiments, the supercritical fluid and the textile are present in a mass ratio of between 2,250:1 and 11,350:1.

In certain embodiments, the supercritical fluid and the textile are present in a mass ratio of between 4,500:1 and 9,000:1.

In certain embodiments, the at least partially decolorized textile has a color intensity (K/S value) that is at least 70% lower than the color intensity (K/S value) of the dyed textile.

In certain embodiments, the supercritical fluid comprises carbon dioxide; and the extraction is carried out at a pressure between 210 bar and 280 bar and a temperature between 90 ℃ and 130 ℃.

In certain embodiments, the polyester comprises PET.

In certain embodiments, the method comprises contacting the dyed textile with supercritical CO at a pressure between 210 bar and 280 bar and a temperature between 90 ℃ and 130 DEG C ₂ Contacting to extract at least a portion of the disperse dye from the textile to supercritical CO ₂ And forming an at least partially decolorized textile, wherein the dyed textile comprises PET and supercritical CO ₂ And the textile is present in a mass ratio of between 4,500:1 and 9,000:1.

In certain embodiments, the at least partially decolorized textile has a color intensity (K/S value) that is at least 90% lower than the color intensity (K/S value) of the dyed textile.

In certain embodiments, the textile consists of PET.

Advantageously, the methods described herein do not involve any chemical reactions. Since no organic solvents or hazardous chemicals are required in the process described herein, it is relatively harmless and does not negatively impact the structural and physical properties of the textile fibers. The collection and recovery of the extracted disperse dye is accomplished in a straightforward manner by converting the supercritical fluid into a gas in, for example, a separation vessel during the collection of the disperse dye. The overall process is green and more sustainable than bleaching and other current decolorization processes.

Brief description of the drawings

The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements, comprise drawings of certain embodiments in order to further illustrate and clarify the above and other aspects, advantages and features of the present disclosure. It is appreciated that these drawings depict exemplary embodiments and are therefore not intended to limit the scope of the disclosure. The methods described herein will be described and explained with additional specificity and detail through the use of the accompanying drawings.

Fig. 1 depicts a flowchart illustrating an exemplary process for performing the methods described herein.

Fig. 2 depicts a photograph showing the appearance of the original sample 1.

Fig. 3 depicts a photograph showing the appearance of sample 1 after decolorization as described in example 1.

Fig. 4 depicts the decolorization kinetics in example 1.

Fig. 5 depicts a photograph showing the appearance of sample 1 after decolorization in example 2.

Fig. 6 depicts the decolorization kinetics in example 2.

Fig. 7 depicts a photograph showing the appearance of the original sample 2.

Fig. 8 depicts a photograph showing the appearance of sample 2 after decolorization as described in example 3.

Fig. 9 depicts the decolorization kinetics in example 3.

Fig. 10 depicts a photograph showing the appearance of the original sample 3.

Fig. 11 depicts a photograph showing the appearance of sample 3 after decolorization as described in example 4.

Fig. 12 depicts the decolorization kinetics in example 4.

Fig. 13 depicts the appearance of three PET samples before and after decoloring in example 5.

Detailed Description

Provided herein is a method for decolorizing a dyed textile comprising synthetic fibers and a disperse dye, the method comprising contacting the dyed textile with a supercritical fluid to extract at least a portion of the disperse dye from the textile into the supercritical fluid and form an at least partially decolorized textile.

The dyed textiles may be individual staple or filaments, yarns, fabrics, and articles (e.g., garments). Yarns may include, for example, a plurality of staple fibers twisted together, untwisted filaments laid together, filaments laid together with a degree of twist, and single filaments with or without twist. The yarn may or may not be structured. Suitable fabrics may likewise include, for example, woven, knitted and nonwoven fabrics. The garment may be a ready-made garment or an industrial garment. Fabrics and textiles can include household items such as linens, draperies, and trim materials (including automobiles, boats, aviation). The dyed textile may also be chopped and/or flocculated fibers.

In certain embodiments, the synthetic fibers comprise polyesters, polyamides, polyolefins, acrylic fibers, modacrylic fibers, acetate fibers, polyurethanes, or combinations thereof. Exemplary synthetic fibers include, but are not limited to, PET, kevlar, nomex (nomex), spandex, nylon, and the like. In certain embodiments, the synthetic fibers comprise PET. In certain embodiments, the synthetic fibers consist of PET.

The dyed textile substrate may further comprise natural organic fibers and/or semi-synthetic fibers.

The natural organic fibers may be of any plant or animal origin and include, for example, those derived from natural products containing cellulose, such as wood, bamboo, cotton, banana, pineapple, hemp, ramie, flax, coconut, soybean, milk, yucca (hoya), bagasse, kenaf, retting, mular, silk, wool, open-chain rice (cashmere), alpaca, angora, mohair, wool sheepskin, luo Mamao, antelope, and the like.

Semi-synthetic fibers may include, for example, any one or combination of viscose, cuprammonium, rayon, strong fibers (polynosic), lyocell, cellulose acetate, and the like.

In certain embodiments, the dyed textile is an blended fabric substrate comprising synthetic fibers and natural fibers (e.g., PET/cotton blends).

The disperse dye may be any disperse dye known to those skilled in the art. The disperse dye may be E-type, SE-type, S-type, P-type or RD-type disperse dye. In certain embodiments, the disperse dye comprises acridine, anthraquinone, arylmethane, azo, cyanine, diazonium, naphthoquinone, nitro, nitroso, methine, phthalocyanine, quinone, azine, indamine, indophenol, oxazine, oxaketone (oxazone), thiazine, thiazole, xanthene, fluorine, and combinations thereof.

Exemplary disperse dyes include, but are not limited to, 1-amino-2-methylanthraquinone, disperse red 11, disperse blue 3, disperse yellow 54, disperse orange 13, disperse red 54, disperse yellow 9, disperse orange 61, disperse violet 28, disperse orange 44, disperse blue 102, disperse violet B, disperse red 179, disperse orange 1, disperse yellow 211, disperse blue 77, disperse red 92, disperse blue 35, disperse violet 26, disperse red 91, disperse yellow 163, disperse red 54, disperse red 200, disperse yellow HG, disperse black GI, disperse blue 27, su Pu Lasset bright red BD (Supracet brilliant red BD), 2- [ N- (2-cyanoethyl) -4- [ (2, 6-dichloro-4-nitrophenyl) azo ] anilino ] ethyl acetate, disperse black 9, disperse blue 124, disperse violet 17, disperse red 72 disperse orange 5, disperse yellow 82, disperse yellow brown SE-4BR, disperse brown, disperse orange 3GL, disperse gray BL, disperse blue 3GR, disperse blue 359, disperse yellow 79, disperse violet 63, disperse gray N, disperse red 1, disperse red 60, disperse red 4, disperse brown 1, disperse orange 73, disperse black, C.I. disperse red 50, disperse blue 1, disperse orange 31, disperse red 343, disperse blue 3G, 4- [4- (phenylazo) phenylazo ] -o-cresol, disperse blue 7, disperse blue 93, disperse red BFL, disperse red 5, p- [ [ p- (phenylazo) phenyl ] azo ] phenol, C.I. disperse yellow 71, disperse blue 81, disperse orange 47, disperse red 221, disperse red 146, disperse yellow 56, disperse yellow 39, disperse red BLS, disperse orange, 3- [ (2-hydroxyethyl) [4- [ (4-nitrophenyl) azo ] phenyl ] amino ] propionitrile, disperse violet 5, disperse blue FG, disperse blue 281, disperse red 17, disperse dark blue 6G, disperse green disperse brown 3R, C.I., disperse blue A, disperse orange 44, disperse black 3G, disperse black PNR, disperse blue 5R, disperse yellow GL, disperse violet RB, disperse R, disperse black ECY disperse blue 72, disperse blue 148, disperse red 277, 3- [ [2- (acetoxy) ethyl ] [4- [ (4-nitrophenyl) azo ] phenyl ] amino ] propionitrile, disperse blue GB, disperse red 60, disperse violet 33, disperse blue 54, disperse orange 73, disperse blue 56, disperse orange 76, disperse yellow 49, disperse blue BGL, disperse blue 183, disperse red 65, and disperse orange 29, disperse dark blue RE, disperse red 2GH, disperse black JW, disperse yellow brown, disperse red 17, disperse blue BS, disperse blue 26, disperse yellow 104, disperse yellow 126, disperse yellow 64, disperse blue 165, disperse red 74, disperse yellow 114, disperse red 127, disperse red 98, disperse violet RN, disperse red 73, disperse red 13, disperse brown 1, disperse red 86, disperse blue 291, disperse violet 77, disperse blue 143, disperse red 53, disperse orange 41, C.I. disperse red 50, disperse yellow 5GR, disperse black 1, disperse orange 29, 3- [ ethyl [4- [ (6-nitrobenzothiazol-2-yl) azo ] phenyl ] amino ] propionitrile, 1-amino-4- [ (1-methylethyl) amino ] anthraquinone, disperse violet S, disperse yellow FL, 2- [ [4- [ (2-cyano-3-nitrophenyl) azo ] -m-tolyl ] (2-acetoxyethyl) amino ] ethyl acetate, disperse red 97, 2- [ (2-cyanoethyl) [4- [ (6-nitrobenzothiazol-2-yl) azo ] phenyl ] amino ] ethyl acetate, disperse violet 57, disperse orange 45, c.i.60752, disperse brown 19, 2- [ ethyl [ 3-methyl-4- [ (5-nitrothiazol-2-yl) azo ] phenyl ] amino ] ethanol, disperse yellow 184, disperse red jade B, disperse violet RS, disperse orange 25, disperse red 153, disperse red jade s-2GFL, 5- [ (3, 4-dichlorophenyl) azo ] -1, 2-dihydro-6-hydroxy-1, 4-dimethyl-2-oxonicotinonitrile, 3- [ ethyl [ 3-methyl-4- [ (6-nitrobenzothiazol-2-yl) azo ] amino ] propionitrile, disperse violet 96, disperse black KSL, disperse orange 2R, disperse brown l, disperse blue, disperse violet RB, disperse blue, disperse red blue, disperse blue (blue) blue, disperse blue (blue) 153, disperse blue, disperse blue (blue) 3, blue) blue, disperse blue (blue) 2- [ blue 1-red, disperse red 3, 3 red 1,3 red ] 2, 4-hydroxy-1-methyl-3- [ (3-nitrophenyl) azo ] -2-quinolinone, disperse yellow 235, disperse black BSF, disperse yellow 2G, disperse grass green GL, disperse violet DP, disperse violet 26, disperse yellow GSL, disperse violet 2RL, disperse blue 60, disperse yellow SE-FL, disperse yellow 119, disperse blue 284, 4- [ (4-nitrophenyl) azo ] benzene-1, 3-diamine, 3- [4- [ (2-chloro-4-nitrophenyl) azo ] phenyl ] ethylamino ] propionitrile, disperse black D-W, disperse orange 78, disperse dark brown BR, disperse blue 371:1, disperse blue H3R, disperse anthraquinone, disperse yellow RGFL, disperse red RFS, disperse black BLL, disperse gray GMS, disperse black SHN, disperse orange M-G, disperse brown BF, disperse gray, and the like.

In certain embodiments, the disperse dye is selected from the group consisting of disperse orange 30, disperse red 167:1, and disperse blue 56, examples of which are shown below.

Disperse dyes commonly used to dye textiles containing synthetic fibers tend to be hydrophobic compounds with very poor solubility in polar solvents. In order to increase the solubility of disperse dyes in the extraction process, extraction may be performed using a supercritical fluid that is relatively non-polar. Exemplary supercritical fluids include, but are not limited to, carbon dioxide, acetone, methanol, ethanol, propanol, and mixtures thereof. In certain embodiments, the supercritical fluid is carbon dioxide.

In certain embodiments, the supercritical fluid does not comprise a surfactant. In certain embodiments, the supercritical fluid does not comprise a detergent. In certain embodiments, the supercritical fluid does not comprise an enzyme. In certain embodiments, the supercritical fluid does not comprise an inert gas.

The temperature and pressure at which disperse dye extraction is carried out is generally above the critical temperature and critical pressure of the supercritical fluid. In the case where the supercritical fluid is carbon dioxide, the disperse dye extraction can be performed at any temperature above 31 ℃ and at any pressure above 73.8 bar.

In certain embodiments, the disperse dye extraction is performed at the following temperatures: between 60 ℃ and 150 ℃, between 70 ℃ and 150 ℃, between 80 ℃ and 140 ℃, between 90 ℃ and 130 ℃, between 70 ℃ and 110 ℃, between 80 ℃ and 100 ℃, between 85 ℃ and 95 ℃, between 110 ℃ and 150 ℃, between 120 ℃ and 140 ℃, or between 125 ℃ and 135 ℃.

In certain embodiments, the disperse dye extraction is performed at the following pressures: between 140 and 280, between 140 and 260, between 140 and 250, between 140 and 240, between 150 and 280, between 160 and 280, between 170 and 280, between 180 and 280, between 190 and 280, between 200 and 280, between 210 and 280, between 220 and 280, between 230 and 280, between 240 and 280, between 120 and 160, between 130 and 150, between 135 and 145, between 260, between 250 or between 235 and 245.

The supercritical fluid and the textile may each be present in any of the following mass ratios: greater than 1,000:1, greater than 2,000:1, greater than 2,250:1, greater than 4,000:1, greater than 4,500:1, greater than 6,000:1, greater than 6,750:1, greater than 8,000:1, greater than 9,000:1, greater than 10,000:1, greater than 11,250:1, greater than 12,000:1, greater than 13,000:1, or greater than 13,500:1. In certain embodiments, the supercritical fluid and the textile are present in the following mass ratios, respectively: 2000:1 to 14,000:1, 4,000:1 to 13,500:1, 6,000:1 to 14,000:1, 6,750:1 to 13,500:1, 8,000:1 to 14,000:1, 9,000:1 to 13,500:1, 10,000:1 to 14,000:1, or 11,250:1 to 13,500:1.

The color intensity (K/S value) of the at least partially decolorized textile can be at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 95% lower than the color intensity (K/S value) of the dyed textile due to the extraction process. In certain embodiments, the at least partially decolorized textile has a color intensity (K/S value) that is 50% to 97% lower, 60% to 97% lower, 70% to 97% lower, 80% to 97% lower, 90% to 97% lower, or 94% to 97% lower than the color intensity (K/S value) of the dyed textile.

The methods described herein advantageously have minimal impact on the physicochemical and mechanical properties of the decolorized textile, allowing for a wide range of recycling applications for recycled decolorized textiles.

The change in tensile strength of the welt of the at least partially decolorized textile after the dyed textile is subjected to the decolorizing process described herein may be no more than 10%, no more than 9%, no more than 8%, no more than 7%, no more than 6%, no more than 5%, no more than 4%, no more than 3%, no more than 2%, or no more than 1% of the tensile strength of the dyed textile. In certain embodiments, the at least partially decolorized textile has substantially the same tensile strength in the welt direction as the dyed textile.

The warp-wise tensile strength of the at least partially decolorized textile may vary by no more than 10%, no more than 9%, no more than 8%, no more than 7%, no more than 6%, no more than 5%, no more than 4%, no more than 3%, no more than 2%, or no more than 1% of the tensile strength of the dyed textile after the dyed textile is subjected to the decolorizing process described herein. In certain embodiments, the warp-directional tensile strength of the at least partially decolorized textile is substantially the same as the dyed textile.

In certain embodiments, the decolorization process can further include the temperature of the supercritical fluid circulated during the step of extracting the disperse dye. The temperature cycling may reduce the temperature of the supercritical fluid below the supercritical temperature and/or increase the temperature of the supercritical fluid above the supercritical temperature. The temperature cycling may change the state of the supercritical fluid from a supercritical fluid to a state in which at least a portion of the supercritical fluid is not in the supercritical fluid state. Temperature cycling may also promote bubble generation.

In certain embodiments, the decolorizing process can include generating air bubbles in the presence of the dyed textile during disperse dye extraction.

In certain embodiments, the decolorizing process can include agitating the dyed textile. Agitation may come from mechanical agitation using an agitation mechanism, a rotating mechanism, or a washing mechanism similar to a conventional washing machine.

The decolorizing process can further include removing the supercritical fluid and the extracted disperse dye from the at least partially decolorized textile. The supercritical fluid and the disperse dye may be continuously removed by removing a feed of supercritical fluid containing the disperse dye from the decolorizing vessel in a decolorizing process, and wherein the supercritical fluid may optionally be introduced into the decolorizing vessel to maintain the amount of supercritical fluid in the decolorizing vessel. Alternatively, the decolorization process can be operated in batch mode, wherein the supercritical fluid and disperse dye are removed after the decolorization process is completed. In certain embodiments, the same dyed textile may be subjected to multiple decolorization cycles with fresh supercritical fluid, each decolorization cycle removing the supercritical fluid and then replacing the supercritical fluid.

In certain embodiments, the decolorization process further comprises separating the supercritical fluid from the extracted disperse dye after removing the supercritical fluid from the decolorization vessel.

In certain embodiments, the decolorizing process may further include recovering supercritical fluid for additional decolorizing cycles of the same or different dyed textiles. The recovery process may include cooling the supercritical fluid to a liquid state after separation from the disperse dye. The liquid may then be stored in a storage vessel prior to reuse or conversion to supercritical fluid.

In certain embodiments, the decolorization process may further comprise converting the supercritical fluid to a gas after separating the supercritical fluid from the disperse dye. Thus, the recovery process may further comprise converting the gas into a supercritical fluid before being reused in another decolorizing process.

In certain embodiments, the decolorizing process may further include introducing a supercritical fluid into the decolorizing vessel; introducing the dyed textile into a decolorizing vessel; and extracting the dyed textile with a supercritical fluid in a decolorizing vessel. Thus, the gas or liquid may be converted to a supercritical fluid prior to being introduced into the decolorizing vessel. Alternatively, the gas or liquid may be converted to a supercritical fluid in a decolorizing vessel. In certain embodiments, the dyed textile is introduced into a decolorizing vessel prior to introducing the supercritical fluid or liquid or gaseous precursor thereof.

Examples

In the examples described below, PET fabric samples were rolled into porous bundles, and the bundles were then secured in a cylindrical decolorizing container. The heating of the decolorizing vessel is controlled electrically.

Supercritical CO ₂ The feed is compressed by a booster pump and then flows into a decolorizing vessel. Then supercritical CO ₂ Contact the PET fabric and remove the dye. Supercritical CO ₂ And the dissolved dye is discharged from the decolorizing vessel through the porous bundle. Supercritical CO ₂ And finally decompressing the dissolved dye by a decompressing device and flowing through a separating container for separation.

Example 1

A 100% PET fabric sample (sample 1, as shown in fig. 2) of 10g yellow-dispersed orange 30 (withThe original maximum wavelength is 450 nm) is placed in a decolorizing system, and the process steps are shown in fig. 1. The operating temperature ranges from 90 ℃ to 130 ℃ and the pressure is 240 bar. Supercritical CO per gram of fabric ₂ The feed range is 2250g/g to 6750g/g. The appearance of the decolorized samples is shown in fig. 3. The K/S values of the samples before and after decolorization were measured. The detailed results are shown in Table 1, and the decolorization kinetics are shown in FIG. 4.

TABLE 1 at different temperatures and supercritical CO ₂ The percent color intensity of the feed, 240 bar pressure sample 1 decolorized, varied.

Furthermore, for CO in supercritical state ₂ The change in tensile strength after the maximum feed was tested for tear strength (ASTM D1424). The detailed results are shown in Table 2.

TABLE 2 supercritical CO at different temperatures, 240 bar pressure maximum ₂ The percent change in tensile strength of sample 1 decolorized after feeding.

Example 2

10g of a 100% PET fabric sample of yellow-dispersed orange 30 (sample 1, as shown in FIG. 2), having an original maximum wavelength of 450nm, was placed in a decolorizing system, and the process steps were as shown in FIG. 1. The operating temperature is 90℃and the pressure ranges from 140 bar to 240 bar. Supercritical CO per gram of fabric ₂ The feed range is 2250g/g to 6750g/g. The appearance of the decolorized samples is shown in fig. 5. The K/S values of the samples before and after decolorization were measured. The detailed results are shown in Table 6, and the decolorization kinetics are shown in FIG. 6.

TABLE 3 different pressures and supercritical CO ₂ The percent change in color intensity of sample 1 decolorized at 90 ℃ at the feed.

Furthermore, for CO in supercritical state ₂ The change in tensile strength after the maximum feed was tested for tear strength (ASTM D1424). The detailed results are shown in Table 4.

TABLE 4 supercritical CO at different pressures and temperatures of 90 DEG C ₂ The percent tensile strength of sample 1 decolorized after the maximum feed was varied.

Example 3

10g of a 100% PET fabric sample (sample 2, shown in FIG. 7) with a red dispersion of 167:1 (original maximum wavelength 530 nm) was placed in a decolorizing system, the process steps being shown in FIG. 1. The operating temperature ranges from 90 ℃ to 130 ℃ and the pressure is 240 bar. Supercritical CO per gram of fabric ₂ The feed range is 2250g/g to 6750g/g. The appearance of the decolorized samples is shown in fig. 8. The K/S values of the samples before and after decolorization were measured. The detailed results are shown in Table 5, and the decolorization kinetics are shown in FIG. 9.

TABLE 5 different temperatures and supercritical CO ₂ The percent color intensity of the feed, 240 bar pressure sample 2 decolorized, varied.

Furthermore, for CO in supercritical state ₂ The change in tensile strength after the maximum feed was tested for tear strength (ASTM D1424). The detailed results are shown in Table 6.

TABLE 6 supercritical CO at different temperatures and 240 bar pressures ₂ The percent tensile strength of sample 2 decolorized after the maximum feed was varied.

Example 4

10g of a 100% PET fabric sample (sample 3, shown in FIG. 10) with blue disperse blue 56 (with an original maximum wavelength of 620 nm) was placed in a decolorizing system, the process steps being shown in FIG. 1. The operating temperature ranges from 90 ℃ to 130 ℃ and the pressure is 240 bar. Supercritical CO per gram of fabric ₂ The feed range was 2,250g to 11,350g. The appearance of the decolored sample is shown in FIG. 11. The K/S values of the samples before and after decolorization were measured. The detailed results are shown in Table 7, and the decolorization kinetics are shown in FIG. 12.

TABLE 7 different temperatures and supercritical CO ₂ The percent color intensity of the feed, 240 bar pressure sample 3 decolorized, varied.

Furthermore, for CO in supercritical state ₂ The change in tensile strength after the maximum feed was tested for tear strength (ASTM D1424). The detailed results are shown in Table 8.

TABLE 8 ScCO at different temperatures, 240 bar pressure ₂ The percent tensile strength of sample 3 decolorized after the maximum feed was varied.

Example 5

9g of the mixed sample (sample 4, shown in FIG. 13) with color of disperse orange 30, disperse red 167:1 and disperse blue 56 was placed in a decolorizing system, and the process steps are shown in FIG. 1. The sample involved 3g of a yellow 100% PET fabric (as-isInitial maximum wavelength=450 nm), 3g of red 100% pet fabric (original maximum wavelength=530 nm) and 3g of blue 100% pet fabric (original maximum wavelength=620 nm). The operating temperature was 90℃and the pressure 240 bar. Supercritical CO per gram of fabric ₂ The feed was 9,000g. The appearance of the decolored sample is shown in FIG. 13. The K/S values of the samples before and after decolorization were measured. The detailed results are shown in Table 9.

Table 9. Percent change in color intensity for sample 4 decolorized.

Table 10. Percent tensile strength change for sample 4 decolorized.

The present disclosure is not to be limited to the specific embodiments described herein, which are intended as illustrations of various aspects. As will be apparent to those skilled in the art, many modifications and variations are possible without departing from the spirit and scope thereof. Functionally equivalent processes within the scope of the present disclosure, other than those enumerated herein, will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that the present disclosure is not limited to particular methods, reagents, compounds, compositions, or biological systems, which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

Claims

1. A method for decolorizing a dyed textile comprising synthetic fibers and a disperse dye, the method comprising contacting the dyed textile with a supercritical fluid to extract at least a portion of the disperse dye from the textile into the supercritical fluid and form an at least partially decolorized textile.

2. The method of claim 1, wherein the supercritical fluid does not comprise a surfactant.

3. The method of claim 1, wherein the synthetic fibers comprise polyesters, polyamides, polyolefins, acrylic fibers, acetate fibers, polyurethanes, or combinations thereof.

4. The method of claim 1, wherein the synthetic fibers comprise polyethylene terephthalate (PET).

5. The method of claim 1, wherein the disperse dye is selected from the group consisting of: acridine, anthraquinone, arylmethane, azo, cyanine, diazo, nitro, nitroso, phthalocyanine, quinone, azine, indamine, indophenol, oxazine, oxaketone, thiazine, thiazole, xanthene, fluorine, and combinations thereof.

6. The method of claim 1, wherein the supercritical fluid comprises carbon dioxide, acetone, methanol, ethanol, propanol, and mixtures thereof.

7. The method of claim 1, wherein the extraction is performed at a temperature between 60 ℃ and 150 ℃.

8. The method of claim 1, wherein the extracting is performed at a temperature between 90 ℃ and 130 ℃.

9. The process according to claim 1, wherein the extraction is carried out at a pressure between 140 bar and 280 bar.

10. The process according to claim 1, wherein the extraction is carried out at a pressure between 210 bar and 280 bar.

11. The method of claim 1, wherein the at least partially decolorized textile has a tensile strength that does not vary by more than 10% of the tensile strength of the dyed textile.

12. The method of claim 1, wherein the supercritical fluid and the textile are present in a mass ratio of between 2,250:1 and 11,350:1.

13. The method of claim 1, wherein the supercritical fluid and the textile are present in a mass ratio of between 4,500:1 and 9,000:1.

14. The method of claim 1, wherein the at least partially decolorized textile has a color intensity (K/S value) that is at least 70% lower than the color intensity (K/S value) of the dyed textile.

15. The method of claim 1, wherein the supercritical fluid comprises carbon dioxide; and the extraction is carried out at a pressure between 210 bar and 280 bar and a temperature between 90 ℃ and 130 ℃.

16. The method of claim 15, wherein the supercritical fluid and the textile are present in a mass ratio of between 4,500:1 and 9,000:1.

17. The method of claim 16, wherein the polyester comprises PET.

18. The method of claim 1, wherein the method comprises contacting the dyed textile with supercritical CO at a pressure between 210 bar and 280 bar and a temperature between 90 ℃ and 130 ℃ ₂ Contact, thereby willAt least a portion of the disperse dye is extracted from the textile into the supercritical CO ₂ And forming an at least partially decolorized textile, wherein said dyed textile comprises PET and said supercritical CO ₂ And the textile is present in a mass ratio of between 4,500:1 and 9,000:1.

19. The method of claim 18, wherein the at least partially decolorized textile has a color intensity (K/S value) that is at least 90% lower than the color intensity (K/S value) of the dyed textile.

20. The method of claim 18, wherein the textile consists of PET.